CloudLinux OS 7 typically used a modified Linux kernel known as the "CloudLinux Kernel" or "KernelCare." This kernel was designed to improve the stability and security of shared hosting environments.

The CloudLinux Kernel includes features like Lightweight Virtual Environment (LVE), CageFS, and SecureLinks, which are specific to CloudLinux's unique server management approach.

Regarding the classification of the CloudLinux Kernel as "hybrid", it's important to note that the term "hybrid kernel" is generally used to describe an operating system kernel that combines elements of both monolithic and microkernel designs. The CloudLinux Kernel itself is based on the Linux kernel, which is monolithic in nature.

If there have been significant changes or updates to CloudLinux OS after September 2021, I wouldn't be aware of them. Therefore, for the most accurate and up-to-date information, I recommend consulting the official CloudLinux documentation or contacting CloudLinux support directly.